Vaporizer



F. R. ERBACH Jan. 17, 1933.

VAPORI ZER Filed April 26, 1928 2 Sheets-Sheet l INVENTOR.

cw mm ATTORNEYS.

Jan. 17, 1933. F. R. ERBACH ,3

' VAPORIZER Filed April 26, 1928 2 Sheets-Sheet 2 HI M I N VEN TOR. I

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A TTORNEYS Patented Jan. 17, 1933 UNITED STATES PATENT OFFICE FREDERICK R. ERBACH, OF DETROIT, MICHIGAN, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE GUARDIAN TRUST COMPANY, OF CLEVELAND, OHIO, AS TRUSTEE vAromzna Application filed April 26,

occupy only a minor portion of the space in a chamber to be cooled and which contains a total heat transfer wall surface at least equal to the total wall area of the chamber.

Another object of my invention is to provide'a novel type of vaporizer which is of particularly compact design.

Other objects of the invention, more or less ancillary or incidental to the foregoing,

will appear from the following description in connection with the accompanying drawings.

In the drawings Fig. 1 is a perspective View of; a cabinet having refrigerating apparatus incorporating my invention associated therewith;

Fig. 2 is an elevational View partially section, illustrating the preferred embodiment of my invention; i

Fig. 3 is an end view of the vaporizer as sociated with a wall'of the cabinet;

i .Fig. 4 is a sectional view -of the vaporizer taken on line IV-IV of Fig. 3;

Fig. 5 is a plan view of a modified form of the vaporizer;

Fig. 6 is an end elevational view of thesame;

Fig. 7 is a plan view of another modified form of vaporizer incorporating my invention; .7 Fig. 8 is an end elevational view of the same.

Referring now to the drawings by characters of reference, 10 illustrates a food storage display caseproviding a compartment or chamber for the reception of food, or the like, which is to be maintained at a sub- .stantially low temperature by mechanical re 1928. Serial No. 272,918.

frigerating apparatus. With the exception of thevaporizer, which forms the subject of this invention, any conventional type of mechanical refrigerating apparatus can be utilized and reference may be had .to Patent No. 1,476,546 for a specific illustration and description of the compressor-condenser and control mechanism which can be associated with my invention. A compressor-condenser unit 11 is preferably arranged exteriorly of the display case, the compressor being driven by the electric motor .12 which is controlled by automatic switch mechanism contained within the casing 13, the condenser being of the water cooled type arranged above and surrounding the compressor.

. The vaporizer 14, which forms the subject of this invention, is preferably of the flooded type and is adapted to contain a body of volatile .liquid refrigerant, preferably sulphur dioxide, and oil which are partially mutually soluble, the oil being of less specific gravity than the refrigerant. The vaporizer consists, generally, of a container portion 15 and looped tube extensions 16, suitable means being associated with the system for'automatically maintaining a substantiallyconstant quantity of both refrigerant and of oil in the vaporizer, and such control means being preferably arranged, within the container.

The container 15 is constructed of metal of a character through which heat can be readily transmitted, and is, preferably, cylindrical in form, and includes an integral wall 17 at one end and an aperturedring mem* ber 18 secured to the other end, the aperture in the ring member being closed by the detachable plate 19.

The means for controlling the quantity of refrigerant and oil in the container are pref-" erably carried by the detachable closure plate 19 and are removable therewith, as a unit, from the container. The closure plate is provided with a refrigerant inlet passage-20 ocated centrally and adjacent the bottom thereof, and with theinner end of this passage is associated'a valve stem 21 which is operated automatically by a float carrying arm22 to which it is pivotally attached. The

float carrying arm is pivoted to a bracket 23 which is detachably secured by screws 24 to a boss protruding from the inner wall of the closure plate. A fitting 25 is secured to the exterior face of the closure plate so that it communicates with the passage 20, and a conduit 26 extends from the condenser outlet to the fitting for supplying liquefied refrigerant and oil to the vaporizer when the valve is open. An Outlet passage 27 is formed through the closure plate, above the inlet passage, and receives one end of an outlet tube 28. The outlet tube projects inwardly of the container, entirely above the liquid level therein, the open inner end there- .of being preferably in the vapor space and adjacent the top central portion of the container to receive the vaporized refrigerant at a point where there is the least liquid particles. A fitting 29 is secured to the outer face of the closure plate so tl at it communicates with the passage 27 and the tube 28, and a return conduit 30 extends from such fitting to the compressor. A baflle member 31 extending from the closure plate is arranged directly beneath the tube to subdue the agitation at the surface of the liquid therebelow caused by the incoming liquid entering the colder refrigerant in the container.

The liquid refrigerant and oil, in solution, passes from the inlet conduit into the container when the valve is open, due to pressure exerted by the compressor. The valve mech-' anism is mounted and adjusted to open when the body of liquid within the vaporizer falls below a predetermined level and to close when such level is present, so that as the liquid refrigerant vaporizes the valve will intermittently open automatically and admit more liquid from the feed conduit. A. definite quantityof oil passes into the vaporizer with the refrigerant due to their solubility, and there will be two definite liquid layers formed in the container because the oil being of lower specific gravity than the refrigerant will collect in the upper level when the refrigerant with which it is in solution vaporizes. liquid below the horizontal plane indicated by 32 will consist of refrigerant and a quantity of oil which is mutually soluble therewith, while the liquid above the plane 32 will .movement of gasified refriger nt from the be principally oil with a small quantityof refrigerant in solution therewith.

I have found that with a liquid condition of such character, wherein a layer of oil. over: lies the refrigerant, the efficiency of the apparatus is reduced-because of the retarding effect of the oil layer upon' the release of gasified refrigerant therebelow to the vapor space thereabove. In other words, the layer of oil has sufficient viscosity to restrain the normal body of liquid refrigerant to the vapor space above the liquid. I a considerable thickness of oil layer is not maintained at the top of The aseasaa the liquid in a vaporizer of the character illustrated, ebullition will throw liquid refrigerant particles into the vapor space and they will travel into the return conduit and vaporize therein causing frosting, and hence it is desirable to maintain a substantial quantity of oil in the vaporizer even though it reduces the efficiency. Vaporizers of the type just referred to are constructed with pipe loops,

munication with the lower refrigerant body in the container, or with only one end communicating with the liquid refrigerant body and the other end communicating with the vapor space well above the liquid level. With tube loops having both ends below the liquid level in the container, there is no definite path in which the refrigerant gasifying therein will escape, and as a matter of fact, I have found that it escapes from both ends, and further, such escape is retarded by the oil layer in the container so that as a consequence there are spasmodic releases of the gasified refrigerant causing a reduced efliciency of the vaporizer and the system. With loops having one end communicating with the container well above the liquid level, the oil layer and the liquid layer will originally be in the same respective planes as in the container, but as the liquid refrigerant vaporizes and escapes or duct means, extending from the a 7 liquid container, either with both ends in comlayer in the tube loop, thus increasing the resistance to the passage of gasified refrigerant therethrough causing a gradually increasing amount of gasified refrigerant to return to the container through the inlet portion of the tube loop. LEventually the'oil will accumulate iii the pipe loop to a degree such that gasified refrigerant will not penetrate the same, thus causing the refrigerant which vaporizes to return to the container through the inlet portion of the tube loop. Such conditions materially reduce the heat transfer efficiency of thetubc loop and the system.

In order, therefore, to provide an evaporator with duct extensions adapted to produce maxiinum heat transfer, I have formed and associated the loops 16 with a container in a novel manner. This-result is promoted by arranging the lower inlet leg 16 of the loops in a plane adjacent to but at least below the top) of the; refrigerant layer in the container, and by arranging the return leg 16' of the loops in-a plane adjacent thetop level of and at least partially above the oil layer loops project through the end 17 of the container at such positions and are secured thereto in open communication with the interior of the container. The tubes are preferably formed of copper, or a similar material having rapid heat transfer qualities, the two legs being preferably of uniform cross section and substantially parallel and extending in a horizontal plane. The distance between the upper and lower legs is preferably as little as possible so that the resistance of forces and pressure to flow from the lower legs to the upper legs will be minimum. It will be seen that the major portion of the duct in the upper legs of the pipe loops are above the liquid level in the pipe loops and the container, and thus as the resistance is less in the upper legs than in the lower legs which contain liquid refrigerant and oil, the refrigerant vaporizing in the loops will travel in the path of least resistance which is through the unrestricted duct in the upper leg to the vapor space in the container above the liquid vaporization in the tubes results in violent ebullition therein, and because of the arrangement of the tube loops with the container, a very rapid circuitous circulation of refrigerant will'take place in the single direction of flow from the container through the lower legs of the loops and through the upper legs of the loops back into the container.

The vaporized refrigerant and liquid refrig--' erant particles will in this manner form a flowing stream which will sweep the entire inner wall of the leg of the pipe loops above the portions containing liquid refrigerant, and thus a substantially uniform heat transfer results from any point of the pipe loops so that maximum heat transfer is provided. A further advantage of this arrangement of the loops with respect to the liquid level is that when vaporization is nottaking-place the oil layer in. the loops formed at the top portion of the bend in the loops will be positively moved into the container with a minimum degree of ebullition, and further after such oil layer is initially moved will not accumulate again while any material vaporization is in progress because of the circulation of the refrigerant in a definite direction through the pipe loops.

The pipe loops should be disposed in a substantially horlzontal plane and relatively close together for two reasons. 'The return legof the loops must be disposed at least partially above the level of the oil in the container but sufliciently close thereto to pre-. vent material opposition to the vomiting of oil and a small quantity of liquid refrigerant through the return leg of the loops with 7' the gasified refrigerant. The inlet leg of the pipe loops must be below the level of the refrigerant in the container but 1101?? sufiicientlylower that any material pressure will .be exerted upon the liquid in the lowermost portion thereof by the column of liquid above it in the loop, as the rate of vaporization of the refrigerant decreases with an increase ofpressure thereon.

Another feature of my invention resides in the particular location of the return tube 31 and the arrangement for returning sufiito the wall of the container.

of peripherally arranged openings. 39 are cient oil by gravity to maintain a substantially constant quantity of oil in the vaporizer, so that a minimum quantity of vaporizing refrigerant will contact with the return ing being above the normal oil level. When vaporization takes place in the container, the liquid level approaches the passage 40, andany surplus oil above the predetermined desired quantity in the container will flow through the passage and travel by gravity 'through the tube into the return conduit 30 leading back to the compressor. With the oil outlet arranged normally above the oil level, there will. be less liquid refrigerant passing through the passage 40 thus reducing the quantity of liquid refrigerant vaporizing in the return conduit, so that frosting of the return conduit is substantially eliminated due to this cause.

The circuitous movement of the refrigerant through the tubes normally causes intense agitation of the liquid in the container, and in order to subdue the same I have provided a baflle 41 which extends in a vertical plane transversely across the container. The bafile is bent outwardly at its periphery to form a flange which is soldered or welded A plurality formed'through the baflle to permit the passage of liquid and gas therethrough. This battle is necessarily arranged intermediate the end wall 17 and, the valve float, the location of the same being adjacent the end wall 17 regardless of the form of the refrigerant control.

In order to further increase the efiiciency of the vaporizer, I provide a plurality of similar spaced heat conducting fins 42 which are designed to have a total surface area preferably greater than the area'of the walls of the chamber to be refrigerated. The vaporizer, including the container, tubes and fins, is compact and occupies a minor portion of the space within the chamber which it refrigerates. The compactness and efficiency of a vaporizer are important factors in commercial"requirements,and this vapori-zer has such qualities. The fins are constructed to lend themselves to rapid and economical manufacture and assembly upon the pipe loops. Each fin 42 is formed ofa sheet of cuprous material, or material having similar heat transfer characteristics, and

the vaporizer,

vaporizer to the circulation of the air in the and in this re-" chamber being refrigerated, spect efficiency is helped by not unduly retarding the speed of thefair circulating by which circulation in the structure shown in the drawings is induced solely by convection. I 1 W The fins are of a similar area in cross section to the container so that a similar general section of the vaporized results. The

/ fins are preferably formed and associated With such character of fins with the pipe loops 16 so that any point on the periphery of each loop is substantially the same distancefrom a portion of the pipeloops. Thus the heat transferred has substantially the same distance to travel from all peripheral portions of the fins to the pipe loops, and this will result in a uniform transfer and maximum efiiciency of the fins.

contacting with loops of which .all portions will transfer a uniform maximum amount seen that the air passing thereby will be maintained at-a uniform temperature with a compact structure. Further, a compact vaporizer, occupying only a minor portionof heat transfer surface is of air in the chamber;

is provided and the great enough total area to reduce the running time of the apparatus to a minimum for maintaining a predetermined temperature, and also, any degree above freezing can be maintained therewith without abstracting moisture from the air in the chamber'and collection of the the space in the chamber,

same on the vaporizer so long as the'tempere? at ure of the vaporizer is above the dew point corresponding to the relative humidity Vantage of not deteriorating the food by the abstraction of moisture, the vaporizer under the above mentioned temperature and humidity conditions hasthe advantage of not requiring defrosting and eliminates the necessity of providing means for collecting con-- densation. Y

The vaporizer is arranged within-the display case 10 and is secured in desired position in the chamber by supporting means associated with each end thereof. The means for supporting each end of the vaporizer are similar, and-include a bar 44 fastened to the inner top wall of the casing by screws 45, a spacing collar 46 being provided intermediate the bar and the wall.- Two bracket members 47' extend through of the bars and are threaded and positioned relative to the bar by nuts 48 and 49'. The lower end ofthe brackets are curved to enof heat, it will be.

of the N In addition to the ad apertures in the ends e beneath the upper legs of the' tube loops.

the casing can be reguand 6,1 have illustrated a. modis I' fied form of vaporizer incorporating my invention, however, in this instance the tube loops 50 extend from the side of the con tainer 15 rather than from the end thereof as in the preferred form. In addition, there are four tube loops illustrated and the fins 51 are assembled in two rows, each thermally contacting with two pipe loops. The end fins of each row are secured together by a connecting member 52 which lends rigi ity to the structure. In ll other particulars this modified form; of vaporizer corresponds to the first described form.

In Figs. 7 and 8, I have illustrated'a second modified form of vaporizer which incorporates the principles of my invention. This vaporizer is similar to the preferred form except that a single tube loop 53 is employed, and smaller fins 54 are associated with the tube loop.

Various changes can be madein the va-' porizers described without departing from the spirit of my invention and the scope of what I claim.

Iclaim:

1. A refrigerant evaporating unit comprising a refrigerant receiving vessel, means as- .sociated )with the vessel for maintaining a constant quantity of liquid therein, a heat exchange conduit communicating atone end with the interior of the vessel both above and below the liquid level therein, and means associated with the opposite end of the conduit for providing communication with the vessel below the liquid level therein.

2. A refrigerant evaporating unit comprising a refrigerant receiving. vessel, means for maintaining a constant quantity of liquid-in posed with said vesselboth above and below the liquid level therein, andmeans for supplying liquid from the receptacle to the remote ends of the conduits. a l 3. A refrigerant evaporating unit compris ing a refrigerant receiving vessel, means for conduits communicating at one endv said vessel, a plurality of horizontally disa maintaining a constant quantity of liquid in said vessel, a plurality of horizontally disposed conduits each communicating at one" end with the receptacle both above and below the liquid level therein, heat exchanging fins arranged along said conduits in perpendicular relation thereto, and means associated with the opposite ends of the conduits for providing communication with said receptacle below the level of liquid therein.

4. A refrigerant. evaporating unit comprising a refrigerant receptacle, a float arranged in said receptacle for actuating a valve to maintain a constant quantity of liquid therein, ,a plurality of loops of finned conduit associated with the receptacle for circulating liquid to and from the receptacle, and a bafiie arranged between the float and the loops for I maintaining arelatively static condition of the liquid in the receptacle.

5. A refrigerant evaporating unit comprising a horizontally disposed cylindrical refrigerant receiving vessel having a closed 1 end, a removable head for the opposite end, means' associated with the head for admitting refrigerant to and withdrawing refrigerant from the vessel including means for maintaining a constant quantity of liquid within the vessel, a plurality of horizontally disposed conduit loops communicating with the vessel, said loops each having horizontally disposed parallel legs arranged one above another the upper leg of each loop communicating with the vessel both above and below theliquid level therein, the lower leg of each loop communicating with the vessel below the liquid level therein, the corresponding leg of each loop being disposed in spaced relation in the same horizontal plane,

and heat absorbingfins arranged in parallel relation along said legs transversely intersecting the latter.

6. A refrigerant evaporating unit comprising a refrigerant receivm vessel, means associated with the vessel or maintaining a constant quantity of liquid therein, a heatexchange conduit conununic'ating atone end with the interior of the vessel both above and; p

.35 below the liquid level therein, means asso- 55 nature.

ciated with the opposite end of the conduit for providing communication with the vessel below the liquidlevel therein, and a heatexchanging fi'n associated with said conduit inthermal contacting relation thereto.

7. A refrigerant evaporating unit com- I prising arefrigerant receiving vessel, means associated with the vessel for maintaining a constant quantity of liquid therein, a heatexchange conduit communicatingat one end with the interior of the vessel both above and below the liquid level therein, means'associated with the opposite. end of 'the' c0n-. duit for providing communicationwith the vessel below the liquid level therein, and a heat-exchanging fin disposed in thermal contact with said conduit and extending in a plane transversely intersecting the latter. In testimony whereof I have aflixed my'sig- FREDERICK RAERBACYH. 

